After holding the weight for so long, the muscle would get tired, in an effort to tell the brain to stop holding the weight because the muscle fibers cannot handle it any more. Lactic acid is a by-product during muscle contraction that leads to the pain.
When Earth passes directly between the Sun and the Moon, its shadow creates a lunar eclipse. Lunar and Solar eclipses happen with almost the same amount of frequency. Lunar eclipses are more visible because the Earth casts a bigger shadow on the Moon during a Lunar eclipes, but during a Solar eclipes the Moon casts a bigger shadow on Earth so its less visible.
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A good example of scientific theory repeated many times is the “theory of relativity” proposed by Albert Einstein in 1915 which was tested and repeated in 1919 at the time of solar eclipse which was later repeated again by many scientists.Explanation:
It's a good fact. Hope this helps
This is one reason that the same hormone can trigger different effects in different tissues. For example, epinephrine binds to four different receptors in different tissues-- eliciting a different response from each.
